Brain angiotensin receptors and binding proteins

Area of Science:

• Neuroscience
• Endocrinology
• Biochemistry

Background:

• The brain angiotensin system involves angiotensin II (Ang II) and its AT1 and AT2 receptors, which are G protein-coupled receptors (GPCRs).
• Research is uncovering new signal transduction pathways and protein interactions for Ang II receptors.
• A controversy exists regarding the specific active angiotensin peptide acting on brain AT1 receptors.

Purpose of the Study:

• To review classical and novel aspects of the brain angiotensin system.
• To address the controversy surrounding the active angiotensin peptide for brain AT1 receptors.
• To summarize the discovery and characteristics of a novel, brain-specific angiotensin peptide binding site.

Main Methods:

• Literature review of classical and novel findings on the brain angiotensin system.
• Discussion of established knowledge on AT1 and AT2 receptor subtypes.
• Summary of recent research on a novel angiotensin binding site, including its properties and potential activators.

Main Results:

• The brain expresses both AT1 and AT2 angiotensin II receptors, which are GPCRs.
• A novel, brain-specific, membrane-bound binding site for angiotensin peptides, independent of AT1 and AT2 receptors, has been identified.
• This novel site is unmasked by p-chloromercuribenzoic acid (PCMB) within a specific concentration range, suggesting dependence on the brain's redox state.

Conclusions:

• The brain angiotensin system is complex, involving known receptors and a newly discovered binding site.
• The novel binding site's characteristics and its dependence on brain redox state warrant further investigation.
• This site may mediate non-traditional actions of Ang II in the brain, such as dopamine release, or function as a peptidase or clearance receptor.